# Resolution of vectors

What is the fundamental basis of resolution of vector. Suppose we have a vector $\vec{mg}$, now we resolve it into two components, horizontal and vertical. My question is what is the basis for telling that this is the horizontal and this is the vertical component since the Cartesian plane can be drawn on any direction.

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Ok.. another question why was an electron's charge called negative and proton's positive? – Sreekanth Karumanaghat Apr 10 '13 at 12:47

You're right that the co-ordinates can be written in any direction. But, there's always a left-right (horizontal) co-ordinate, bottom-top (vertical) co-ordinate and out-in (normal) co-ordinate. You can choose any of these co-ordinates as $x$, $y$ and $z$. But at any given time, there's gonna be an axis for each of these co-ordinates. It's not a rule that $x$ axis should be horizontal and $y$ should be vertical